Tungsten lamp as radiation standard and the emissivity effects

Abstract

The derivative of the detected incidance in a wavelength interval with respect to temperature includes two terms. The first term depends on the change in blackbody emission and the second one on the change of emissivity with temperature. The error of neglecting the second term is analyzed and evaluated for a standard radiation source, a tungsten lamp. In this case, the error changes form a negligible amount of 6% to a significant value of more than 45%.